Heat pipe

Abstract

Provided is a heat pipe which is installed in a cold region in a bottom heat posture in which a longitudinal direction of a container is substantially in parallel with a gravitational direction, is capable of preventing the container from deforming even when a working fluid has become frozen, and has excellent heat transport properties.

What is claimed is: 
     
       1. A heat pipe comprising:
 a container being of a tubular shape and having an inner wall surface, an end surface of one end part of the container and an end surface of another end part of the container being sealed, a groove part being formed on the inner wall surface of the container; 
 a sintered body layer being provided on an inner wall surface of the one end part of the container and being formed by sintering a powder; and 
 a working fluid sealed in a hollow part of the container, 
 wherein the sintered body layer has a first sintered part being located on a side of the end surface of the one end part and a second sintered part being continuous with the first sintered part and being located on a side of the other end part, 
 wherein an average primary particle diameter of a first powder being a raw material of the first sintered part is smaller than an average primary particle diameter of a second powder being a raw material of the second sintered part, 
 wherein a protruding sintered body is further provided, the protruding sintered body protruding from the sintered body layer in a cross section perpendicular to the longitudinal direction of the container and being formed by sintering a powder, and 
 wherein in the cross section perpendicular to the longitudinal direction of the container, (an area (A1) of the sintered body layer+an area (A3) of the protruding sintered body) divided by an area (A2) of the hollow part is 1.2 to 2.0. 
 
     
     
       2. The heat pipe according to  claim 1 , wherein in the longitudinal direction of the container, a length of the first sintered part divided by a length of the second sintered part is 0.2 to 3.0. 
     
     
       3. The heat pipe according to  claim 1 , wherein a ratio of the average primary particle diameter of the first powder to the average primary particle diameter of the second powder is 0.3 to 0.9. 
     
     
       4. The heat pipe according to  claim 1 , wherein a wall thickness (T1) of the container in a bottom portion of the groove part divided by a thickness (T2) of the sintered body layer on a top portion of the groove part is 0.30 to 0.80. 
     
     
       5. The heat pipe according to  claim 1 , wherein in the cross section perpendicular to the longitudinal direction of the container, an area (A1) of the sintered body layer divided by an area (A2) of the hollow part is 0.30 to 0.80.